Cardiometabolic effects of genetic upregulation of the interleukin 1 receptor antagonist: a Mendelian randomisation analysis

Background To investigate potential cardiovascular and other effects of long-term pharmacological interleukin 1 (IL-1) inhibition, we studied genetic variants that produce inhibition of IL-1, a master regulator of inflammation. Methods We created a genetic score combining the effects of alleles of two common variants (rs6743376 and rs1542176) that are located upstream of IL1RN, the gene encoding the IL-1 receptor antagonist (IL-1Ra; an endogenous inhibitor of both IL-1 alpha and IL-1 beta); both alleles increase soluble IL-1Ra protein concentration. We compared effects on inflammation biomarkers of this genetic score with those of anakinra, the recombinant form of IL-1Ra, which has previously been studied in randomised trials of rheumatoid arthritis and other inflammatory disorders. In primary analyses, we investigated the score in relation to rheumatoid arthritis and four cardiometabolic diseases (type 2 diabetes, coronary heart disease, ischaemic stroke, and abdominal aortic aneurysm; 453 411 total participants). In exploratory analyses, we studied the relation of the score to many disease traits and to 24 other disorders of proposed relevance to IL-1 signalling (746 171 total participants). Findings For each IL1RN minor allele inherited, serum concentrations of IL-1Ra increased by 0.22 SD (95% CI 0.18-0.25; 12.5%; p=9.3 x 10(-33)), concentrations of interleukin 6 decreased by 0.02 SD (-0.04 to -0.01; -1,7%; p=3.5 x 10(-3)), and concentrations of C-reactive protein decreased by 0.03 SD (-0.04 to -0.02; -3.4%; p=7.7 x 10(-14)). We noted the effects of the genetic score on these inflammation biomarkers to be directionally concordant with those of anakinra. The allele count of the genetic score had roughly log-linear, dose-dependent associations with both IL-1Ra concentration and risk of coronary heart disease. For people who carried four IL-1Ra-raising alleles, the odds ratio for coronary heart disease was 1.15 (1.08-1.22; p=1.8 x 10(-6)) compared with people who carried no IL-1Ra-raising alleles; the per-allele odds ratio for coronary heart disease was 1.03 (1.02-1.04; p=3.9 x 10(-10)). Perallele odds ratios were 0.97 (0.95-0.99; p=9.9 x 10(-4)) for rheumatoid arthritis, 0.99 (0.97-1.01; p=0.47) for type 2 diabetes, 1.00 (0.98-1.02; p=0.92) for ischaemic stroke, and 1.08 (1.04-1.12; p=1.8 x 10(-5)) for abdominal aortic aneurysm. In exploratory analyses, we observed per-allele increases in concentrations of proatherogenic lipids, including LDL-cholesterol, but no clear evidence of association for blood pressure, glycaemic traits, or any of the 24 other disorders studied. Modelling suggested that the observed increase in LDL-cholesterol could account for about a third of the association observed between the genetic score and increased coronary risk. Interpretation Human genetic data suggest that long-term dual IL-1 alpha/beta inhibition could increase cardiovascular risk and, conversely, reduce the risk of development of rheumatoid arthritis. The cardiovascular risk might, in part, be mediated through an increase in proatherogenic lipid concentrations. Copyright (C) The Interleukin 1 Genetics Consortium. Open Access article distributed under the terms of CC-BY-NC-ND

Understanding left ventricular assist devices

$\bf Background/Aims:$ Long-term mechanical assist devices are now commonly used in the treatment of severe heart failure to unload the failing ventricle, maintain sufficient end-organ perfusion and improve functional capacity. Depending on the assisted ventricles, 3 categories of long-term assist devices are available: left ventricular assist device (LVAD), biventricular assist device and total artificial heart. Improvements in technology, especially the advent of smaller, durable continuous flow pumps, have led to the use of LVADs in a much broader population of patients in the last 10 years. Both the number of patients living with LVADs and the life expectancy of these patients are increasing. Regarding this growing number of patients with LVAD, intensivists need to understand the physiology of the devices, their functioning, potential complications and their management. $\bf Methods:$ We performed a narrative review of relevant medical literature regarding the physiology of patients with LVAD and management of common complications relevant to the critical care physicians. $\bf Results:$ The most frequent complications occurring in the LVAD patients after the post-operative period are bleeding, driveline infections, thrombosis, device malfunction, right ventricular failure and arrhythmias. Bleeding is the most frequent adverse event in LVAD due to a combination of anticoagulation and acquired von Willebrand disease secondary to shear stress produced within the pump. Their management includes antiplatelet therapy arrest, reduction of the anticoagulation regimen and specific therapy if feasible. Infection is the second most common cause of death after cardiac failure in LVAD patients. All infections must be aggressively treated to avoid seeding the device. Device thrombosis can develop even when patients are adequately anticoagulated and taking antiplatelet therapy because the LVAD is responsible for a chronic hypercoagulable state. $\bf Conclusion:$ Management of these unique patients in the ICU is best accomplished with a multidisciplinary team that includes specialists in advanced heart failure, LVAD nurse coordinators and intensivists